1. Field of the Invention
The invention relates to a rate controlled cardiac pacemaker including a component group to adapt a stimulation rate to a patient's momentary physical stress.
2. Background Information
The publication "Biomedizinische Technik (Biomedical Technology), 34 (1989), pages 191-196" discloses a cardiac pacemaker developed for rate-adaptive single and dual chamber stimulation whose rate control is effected on the basis of measuring the low frequency oscillation spectrum as signals characterizing the patient's activity. For this purpose, the signals are limited in level, are amplified in a frequency selective manner and their spectral component is evaluated for the physical stress.
With the aid of a piezoelectric transducer integrated in the pacemaker housing and with a subsequently connected signal processing circuit, the motion values generated by physical stress can be detected and the pacemaker can be optimally physiologically adapted to the patient's given stress state.
However, the signal processing unit connected to the output of the piezoelectric transducer that is integrated in the pacemaker housing requires additional current beyond that required by the other circuit components of the pacemaker.